oil pump chevy 350

Hi im new here and like what i see. Now i have a question any help will be appreciated. i just bought a 94 chevy truck and the guy i got it from replaced the engine with a used short block with only like 5000 miles on it he put new heads on and after installing everything he could not get oil to the rocker arms. i bought the truck and the first thing i done was pull the distributor and tryed priming the oil pump with an old distributor that i cut the top off of so i can hook my drill to it and prime the oil pump the pump primed up and almost stoped my drill from turning and when i releaced the button the oil pump spun my drill backwards with the pressure that had built up and still no oil to the rockers my question is is this normal or am i going about it wrong or if this is not normal were should i start looking for the problem

A.I am going to assume that the engine did have oil pressure before you bought it. B.There is an oil plug that sits under the rear main bearing cap.If that is missing you will not have oil/pressureC.There are 3 oil galley plugs in the front of the engine behind the timing chain, if they or any of them are leaking you will not have oil/pressureD.There are 3 pipe plugs on the rear of the engine, that are in conjunction with the 3 oil plugs in the front of the engine. If any of those are missing or leaking you will not have oil/pressure.E.If any of the cam bearings turned to block the oil passage holes NO oil/pressure.F.If the Rod or main bearings have too much clearance No or little oil/pressure. Now with all that said please read on.....

I'm guessing you suspected there was an oil/pressure problem?

1.Okay: You need a 1/2 horse power drill.That is a MUST. You will burn a lesser drill up!Make sure your turning the pump CW.

2.You need to make sure that the distributor in reality is only missing the distributor gear.(So the shaft will just spin freely).The only thing in the oil pump is the shaft and NO GEAR to the cam. Because a distributor has segments on the aluminum housing that seal the oil pressure lower in the block. When it seals it creates that segment to run oil pressure up both sides of the block into the oil galley so your oil will reach the cam, lifters, and then the push rods.

3.Once you get that distributor shaft spinning you can turn the Crank Shaft in 1/4 turn segments. That helps change where the cam and lifters are sitting.

4.You should hook an oil/pressure gauge to the connection by the distributor. The oil/pressure you get will depend on the speed of the drill.

5.If the engine is in the truck and you have no oil/pressure. Try adding a quart of oil to the crankcase. If the oil/pressure comes up add another quart. If the oil/pressure is much better.(Suspecting the oil pump pick-up fell off the oil-pump).You can either pull the oil pan, and see if the pick up fell off the pump. Pull the engine and check all the bearing clearances. Braze of mig weld the oil pump pick up to the oil pump."Make sure the pick up is orientated to the oil pan". Before you weld or braze it...

6.If none of those things do it. I would buy an oil-pump priming tool from Jegs P/N 555-23640 $19.99 Next pull the engine if it's in the truck.If you have any questions get back to the forum. Good Luck

i disagree with bob on the fact that there will be no oil pressure if that plug is left out..

i think there will be NO FILTERED OIL if that plug is left out.. the oil will take a short cut bypassing the oil filter circuit right into the rest of the motor...

you can check the location of the hidden plug by removing the oil pressure sending switch and elbow .. marking a clean rigid wire at 8.5 inches... checking the depth of the hidden plug installation...

if somebody put the plug in.. and only drove it even with the level of the main cap mounting surface... it will measure deeper than 8.5 inches from the top of the block.. a incorrectly installed plug will block ALL OIL FLOW into the motor..

there are 3 plugs behind the cam sprocket.. for the 3 oil galleys..

when you spin the oil pump priming tool... or the oil pump drive shaft directly without the priming tool to divert the oil flow around the tool... do you get oil flow directly back into the pan.. you can see it if you can look..

do you get oil pressure at the sending unit hole on the top of the block....

just curious...

do you have all the oil filters that have come off the truck since the loss of oil pressure..

some brands of oil filter elements have been know to fracture under cold oil high rpm situations... clogging the oil galleys.. can you carefully remove the oil filter?? cut the can off??

lastly... DO you feel any resistance when priming the engine with the drill...

i usually use a speed handle to allow me to tell when the oil pump is primed..

could the oil pump screen have fallen off..

could the oil pump have been damaged when the screen was installed..

could the oil pump pressure relief valve be locked open.. or the spring broken.. assembled wrong..

do you get oil at the filter???

do you get oil at the sending unit..

do you get oil down the distributer hole when the oil pump shaft is spun with the housing tool out...

You will also hear the air coming through the lower part of the engine.Then when the air is gone the pressure should build. Wayne. Next time you do the bottom end on a SBC leave that plug out. Then see if you have oil/pressure. maybe when your spinning the oil pump with a hand drill. When that pump is spinning 5,000 to 6,000RPM watch what happens.The rear bearing cap will cover the hole,but not like the plug. The older blocks were actually machined with a step. You could only install the plug just so far....

Thank for the help and yes there seems to be to much resistance when it primes up that is my reason im not sure what are were to start checking. When it primes up its like the oil has no were to go then when i let off the drill all of the pressure makes the drill spin backwards then i can prime it back up and the same thing again this is the first time i have had this happen im gonna pull the engine in the next day or so and start the investigation

redneckjoe69:sounds like something is plugged up? i agree, a teardown is most likely in order. you might be surprised what you find?

Your right Joe:

If the machine shop doesn't remove the cam bearings before they boil of heat the block until the oil flakes off the block, it will collect in behind the cam bearing.The plug the orfice's. There is deffinently something we can't see. If you can't touch it or see it we may miss it too. It could be the pump relief valve is hung open or broken or some crazy thing. Joe I was helping this guy about this time last year. They had a problem that was crazier then this. They installed the engine 70PSI oil Pressure. Drive it 5 to 10 miles ZERO Oil/Press. The engine builder took it back. They installed it the same thing happened. The 3rd time I'm telling this guy to get another short block from the builder. I told the guy for ha-ha's take the block to another machine shop and have them go through it from top to bottom.Now the builder is blaming the roller cam and lifters. You know what it was. The builder didn't install the plug under the rear main, and 3 of the 5 cam bearings were installed upside down. The orfice hole rather then pointing down into the oil galley were pointing up. So then the original builder blamed it on his helper. How lame can one guy get.

i forget who told me that they found a rag left in the oilpan once? i found a dead frog in one of my trannies years ago. still cant figure out how he got in there? lol. but your explation makes more sense Bob. i wonder how much oil pressure this motor makes with the drill running before it spins backwards?

well i got the engine out and assessories off and the oilpan off and found that i have a 4bolt main engine and found some thick greasy oil in the sump of the pan and i think it was deep enough that the oil pump was trying to pump it instead of good oil so i cleaned it all out and then cleaned the pump out im gonna put it all back and fill it back up with oil and see if it will pump oil with all that gone

yertpier:well i got the engine out and assessories off and the oilpan off and found that i have a 4bolt main engine and found some thick greasy oil in the sump of the pan and i think it was deep enough that the oil pump was trying to pump it instead of good oil so i cleaned it all out and then cleaned the pump out im gonna put it all back and fill it back up with oil and see if it will pump oil with all that gone

sounds like that is sludge, caused by someone using cheap, non-detergent oil. does it stain your fingers when you touch it? nasty smell? it might be a good idea to use something to flush the motor out. that sludge is probably built up everywhere in the engine. ive seen it so bad that the oil return in the heads were plugged up. ill bet if you pull the valvecovers and/or intake,...youll see that its everywhere in the motor. at least you know whats going on now.